The invention described herein relates to organophosphine, arsine, or stibine copper(I) mercaptide complexes of the general formula Cu(MR.sub.3).sub.n (SR') where M=P, As, or Sb and R and R' are organo groups and their use as SO.sub.2 indicators and scavengers.
Sulfur dioxide is a major pollutant in a great variety of industrial processes, and the monitoring of this gas is necessary for environmental, health, and engineering considerations. At this time, there are instrumental methods of direct SO.sub.2 gas analysis but virtually no generally recognized dry chemical indicators.